The present invention relates to a method and a device for air conditioning the interior of a motor vehicle equipped with a conventional air conditioning system, in particular, when the vehicle is at a standstill.
Vehicles parked in the sun rapidly reach high interior temperatures, e.g., above 80xc2x0 C. The interior temperature depends on the size of the vehicle, its color, the color and nature of the interior equipment, the outside temperature, the radiant power of the sun, the permeability and size of the window surfaces (heat source of the passenger space) and the thermal resistance of the vehicle body (heat sink). A high interior temperature reduces driving comfort and leads to increased fuel consumption by the air conditioning system, which is then operating at full load at the start of a trip. In the extreme case, engines of standing vehicles may run for hours to avoid this increase in temperature.
Proposals have been made for the air conditioning of standing vehicles, which may involve using processes based on very complicated equipment such as electric compressors, sorption processes and the like.
There are certain methods for air conditioning buildings, whereby air is cooled by humidifying the air conveyed out of such buildings (see Ki November 1994, pages 545-550: Ki Luft-und Kxc3xa4ltetechnik November 1994, T. Rakoczy in xe2x80x9cKxc3xchlung durch Fortluftbefeuchtung bei RLT-Anlagenxe2x80x9d [Cooling by humidifying the outgoing air in ventilation and air conditioning systems] and Ki February 1994, pages 64-65: Ki Luft-und Kxc3xa4ltetechnik, G. Heinrich in xe2x80x9cKxc3xa4lteanlagen mit dem Verdunstungseffektxe2x80x9d [Refrigeration systems with an evaporative effect]). It is believed that one problem with this in the automotive field is the high water consumption, which may necessitate filling up with water, as well as the resulting increased weight and possibly the high air output of the fans.
An object of an exemplary embodiment of the present invention is to permit simple and inexpensive interior air conditioning that does not require much additional energy consumption, in particular, for a standing vehicle (when the engine is not running) in such a way as to permit air conditioning that does not place a burden on the electrical system of the vehicle and can keep the temperature in the interior of a parked vehicle at least in the range of the outside temperature level, or better yet, even lower.
The object may be achieved by using a method that involves the evaporative cooling of water, which is an adiabatic process with air. In humidifying air without any input or output of external energy, there is a shift in the sensible and latent components of the total enthalpy of air, i.e., the absolute atmospheric humidity of the air increases while there is a simultaneous drop in temperature.
From a technical standpoint, this process can be used in two ways: either the outside air intake can be humidified and thus cooled, or as an alternative, the outgoing and therefore hot air from the interior can be humidified and cooled. This can then pre-cool the outside air intake by way of a heat exchanger.
A method according to an exemplary embodiment of the present invention for air conditioning the interior of a motor vehicle equipped with a conventional air conditioning system, in particular, when the vehicle is at a standstill, involves collecting the water of condensation produced in operation of the air conditioning system while driving, and using the collected water to humidify the intake air supplied to the interior or the outgoing air removed from the interior. Thus, when the vehicle is standing still, it is cooled by evaporative cooling, and while driving, the outside air intake may be pre-cooled by the cooled outgoing air by using a heat exchanger.
In an exemplary embodiment of the method according to the present invention, the intake air supplied to the interior of the motor vehicle or the outgoing air removed from it is also overdried by air drying before being humidified.
The water stored in air drying can be expelled thermally and added to the water used for evaporative cooling.
The total water consumption or the cooling power of the xe2x80x9cstanding coolingxe2x80x9d can be controlled and/or regulated optimally as a function of certain parameters such as the outside temperature, the desired interior temperature, the amount of water collected from the air conditioning system and characteristic values of the motor vehicle, for example.
A water reservoir may be provided to supplement the water collected from the air conditioning system in certain situations.
An arrangement for carrying out the exemplary method and achieving the object, as defined above, includes a humidifying turbine provided in an air duct, through which air is supplied to or removed from the interior. The water of condensation collected from the conventional air conditioning system and/or water from the reservoir is sprayed in a fine jet onto the rapidly rotating turbine wheel in the humidifying turbine so that it is thrown outward centrifugally, atomized to fine droplets and vaporized. Unevaporated water can be collected in the worm gear of the humidifying turbine and returned to the process.
The device according to an exemplary embodiment of the present invention may also include a control unit (operatively connected or coupled to the water and coolant circuits) for optimally controlling and/or regulating the total water consumption or the cooling power of the xe2x80x9cstanding coolingxe2x80x9d as a function of certain parameters such as the outside temperature, the desired interior temperature, the amount of water collected and characteristic values of the motor vehicle.
The control unit may be operatively connected or coupled to a remote control unit or a programming unit for selecting certain process variables and/or process sequences of evaporative cooling.